It is known that the wheels of tyred vehicles consist of a cylindrical metal rim having, at the axial extremities, annular containment flanges between which is defined a channel for the slot-in fitting of a tyre.
In fitting configuration, the side portions of the tyre, so-called “beads”, are abutted against the containment flanges.
Inside the tyre, an inner tube can be fitted or, in the case of “tubeless” type tyres, air under pressure can be directly introduced.
To perform the tyre fitting and removal operations onto and from the relative rims, so-called tyre-changing machines are currently used, which permit removing the tyre from the relative rim, e.g. to perform maintenance jobs or the replacement of the inner tube, the rim and/or the tyre itself, and then refitting the same tyre, or a substitute tyre on the wheel rim.
Traditionally, the tyre-changing machines are composed of a base frame supporting grip means and means for starting the rotation of the wheel rim on the machine.
The rotation axis of the grip means and the means for starting rotation can be vertical or horizontal depending on the type of tyre-changing machine.
One or more mobile operating heads are fitted on the base frame and have one or more work tools which cooperate to fit and/or remove the tyre onto and from the rim.
The work tools used have different shapes and dimensions depending on what they are used for.
Some tools, for example, are hook shaped and designed to be inserted between the tyre beads and the corresponding containment flanges of the rim to extract them from the rim channel during the removal phase.
Other tools, on the other hand, have a truncated-cone or cylindrical shape and are fitted in a rotatable way to act as pressing rollers designed to push the tyre beads towards the inside of the rim channel during the fitting phase or towards the outside during the removal phase.
The operating heads fitted on the tyre-changing machine are usually associated with automated operating means, such as pneumatic, hydraulic cylinders or the like, which allow performing the fitting and removal operation with a greater force than a human being.
The operator operates the machine by means of the operating controls governing the movement of the operating heads and the exact operation of the machine is achieved by means of the correct governing of the tools.
Such machines, nevertheless, have a number of drawbacks relating to the fact that they are not very practical to use when performing fitting and removal operations.
With traditional machines in fact, tool movement is inconveniently subject to the professional capacity, skill and experience of the operator.
In particular, it should be noted that some phases of the fitting and removal operations are particularly critical inasmuch as, unless they are correctly performed, the tyre undergoes tensioning and deformation such as to possibly negatively affect integrity and cause serious internal breakages.
Such critical state mostly occurs during operation of the hooked tools to extract the tyre bead from the rim channel and, above all, in the case of particularly delicate tyres such as lowered and runflat tyres.
It is therefore easy to appreciate that the skill of the operator in correctly moving the tools on the tyre represents a current functional limit of tyre-changing machines.
In this respect, furthermore, it is specified that the difficulty in controlling traditional tyre-changing machines inconveniently results in the fact that these can only be operated by skilled and suitably trained personnel, at a fairly heavy cost.